EA anticheat is a kernel level anticheat, which are generally bad for consumers due to them giving malware new targets to get full control of an infected system. Genshin Impact’s kernel anticheat is famously targeted by ransomware as an easier way to gain control of user’s PCs for example. They also don’t work on Linux, which is an obvious problem for Steam Deck users.
It’s not just EA unfortunately. Plenty of multiplayer titles that could run on SD are prevented to do so because of anticheat.
Hell even Roblox used to work until they broke it with anticheat a few months ago. My kid was not happy with that.
They changed Roblox to run on linux again, the changes were available on beta channels for awhile now but just made it back to stable yesterday.